DOI
https://doi.org/10.25772/M9EE-SB88
Author ORCID Identifier
https://orcid.org/0000-0003-4853-1188
Defense Date
2020
Document Type
Dissertation
Degree Name
Doctor of Philosophy
Department
Chemistry
First Advisor
Scott Gronert
Second Advisor
Vladimir Sidorov
Third Advisor
Katharine Tibbetts
Fourth Advisor
Brian Fuglestad
Fifth Advisor
Kenneth Wynne
Abstract
Recent developments in heterogeneous catalysis has led to the conception of single-atom catalysts (SACs), a class of catalysts based on isolated metal atoms anchored to a support scaffold. SACs are often much more reactive and can offer better selectivity when compared to nano-scale catalysts. In order to realize the full potential of SACs, a sound understanding of the underlying catalytic mechanisms is required. However, surface analysis tools can become less effective in studying catalytic mechanisms at the atomic scale. Mass spectrometry has proven to be a robust technique for studying organometallic catalytic mechanisms at the single-molecule level. Using mass spectrometry, we have generated zero-valent metal complexes using Ni, Co, Cu, and Pd active centers. These ions can act as experimental model ions for pristine graphene-supported SACs.
When using Ni as the active center, the model ion is capable of the dehydrogenation of alkanes via two sequential C-H activations. By introducing energy into the system, additional dehydrogenations occur, enabling processes such as the transformation of cyclohexane to benzene. Both the Ni and Co SAC model ions are capable of the selective dehydrogenation of amines and alcohols via a similar dehydrogenation pathway. The Ni, Co, and Pd model ions are capable of engaging in oxidative addition with a variety of polar reagents. The Cu model ion seems to react with polar reagents via one-electron transfer processes. Our work suggests graphene-supported SACs are capable of engaging in dehydrogenation and oxidative addition. Kinetic isotope effects and DFT calculations support the proposed mechanisms.
Rights
© Michael Borrome
Is Part Of
VCU University Archives
Is Part Of
VCU Theses and Dissertations
Date of Submission
12-4-2020